数字电视中视频芯片的自适应去隔行算法研究

文章提出了一种适用于数字电视视频处理芯片上的隔行——逐行格式转换算法。该算法能正确检测出视频的运动和静止信息,从而自适应的采用帧内边缘相关算法或者帧间交织算法进行隔行到逐行的格式转换;并且能准确的检测出并转换具有3-2下拉特征的电影模式视频序列。经仿真验证,该算法与其他算法相比具有占用系统资源少、运算速度快的优点,因此非常适合应用在视频处理芯片中。     

H.264编码模式选择的研究

研究H.264的编码模式选择方案,根据视频序列的时域相关性和空域相关性的关系,模式选择包括帧内预测和帧间预测,帧间预测基于率失真函数,在一帧图像的编码中则可以采用提前终止预测方向的方法降低编码器端的复杂度.     

H.264帧内预测与帧间块模式选择快速算法

针对H.264帧间预测时的多子块模式选择和帧内预测的多模式选择问题,提出了一种实用的基于统计门限的模式快速选择算法,通过门限设定有效限定了编码模式的选择范围.多组视频序列的实验结果表明,基于统计门限的帧内预测模式选择算法在Ⅰ帧的PSNR值有微小变化的情况下,大大降低了编码时间,Ⅰ帧的编码时间降低17%～23%,PSNR下降不到0.4%.基于统计门限的帧间块模式选择算法使得平均PSNR值下降了0.047dB(PSNR最大下降不到1%),但是相对全模式预测时,编码器速度提高了20%～30%.     

一种基于预测模式的H.264/AVC视频信息隐藏改进算法

提出了一种基于帧内预测模式调制的H.264/AVC视频信息改进隐藏算法.选择参考像素亮度值接近的帧内4×4块,通过对预测模式值进行调制以实现隐秘信息的嵌入,而预测模式调制过程是将最优预测模式变为满足嵌入条件的具有率失真开销最小的预测模式,以尽量减小预测模式的改变对视频客观质量的影响.信息的提取过程不需要原始载体视频,也...     

基于低复杂度自适应帧的WVSN视频编码方法

针对WVSN视频节点资源受限与视频编码方法复杂度高等问题,提出一种基于低复杂度自适应帧的视频编码方法。由"隔块-对角线"差异值计算方法求得差异值,建立自适应帧传输机制,避免逐帧判断,减少计算量。帧内图像采用多边形DCT裁剪JPEG压缩,减少二维DCT计算复杂度。实验结果表明,该方法在保证视频质量前提下,能有效降低视频编码复杂度,与无裁剪JPEG图像压缩相比,当前帧、差分帧JPEG压缩DCT计算量分别减少9.4%、56.3%;与M-JPEG视频编码相比,平均PSNR减少3.1%情况下,平均文件大小显著减少55.0%。     

基于编码模式的H.264/AVC视频信息隐藏算法

本文提出一种基于编码模式的H.264/AVC信息隐藏方法,通过调制某些宏块的编码模式,分别在Ⅰ帧、P帧和B帧中嵌入隐秘信息.对帧内4x4预测模式的宏块,是通过调整宏块中某个4×4块的编码模式嵌入隐秘信息;对P帧和B帧其它类型的宏块,则是通过调整宏块的编码模式嵌入隐秘信息,模式调整后对宏块做了优化处理.在模式调制过程中引入率失真代价,取得了较好的率失真平衡,减小了隐秘信息嵌入后对视频质量和视频码流的影响.该算法可以实现隐秘信息的快速提取,满足视频实时处理的要求,实验仿真结果证明了该算法的有效性.     

帧内预测模式快速选择方法研究

H．264标准中的帧内预测方法在很大程度上提高了帧内编码的效率,但同时也增加了编码复杂度。对其中运算量很大的预测模式选择策略和几种改进方法进行了分析,提出了一种自适应的快速预测模式选择方法。该方法主要基于最可能预测模式的自适应阈值和预测模式的选择计算。实验表明,该方法在基本保持了帧内压缩效率的同时,提高了编码的时间效率,而且能够较好支持SIMD指令,有利于汇编指令优化。     

异种帧的相关性对MPEG-2视频源建模的影响

MPEG编码标准通常使用I、P、B三种帧类型。由于P，B帧利用基于I帧的运动补偿技术进行编码，因此同一GOP内不同类型帧之间存在较强的相关性。考虑场景并用二阶自回归模型为I帧建模：（1）对P，B帧采用相地于I帧的一阶合成回归模型建模；（2）分别对P，B帧采用二阶自回归模型建模。实验结果表明，考虑同一GOP内不同帧之间的相关性的模型，比较准确地反映了视频源的统计特征与排队性能。     

最优扫描下新预测模式的帧内预测算法

提出了一种最优扫描下新预测模式的帧内预测算法.首先利用边缘相关性选取最优的扫描方式,然后通过边缘方向估计和统计概率的联合预处理方法缩减单向预测模式的数量,并通过加权内插模型和哈达马变换值(SATD)确定双向预测模式,最后采用最优扫描方式下所选的预测模式进行编码.仿真结果表明,与双扫描双参考帧内预测(DSM_BIP)算法...     

一种亮度融合的视频增强方法

为了提高低照度视频的视觉效果,常常利用高质量白天亮度来增强夜间(低照度)视频.本文提出了一种亮度融合的视频增强方法.首先为了获取白天背景,采用了平均K帧的方法,然后使用Retinex理论,提取了白天背景和夜间视频帧的亮度,同时为了增强夜间移动物,采用帧差法提取了夜间视频帧的移动物,最后利用相同场景的白天背景亮度融合夜间...     

Fast intra prediction mode decision for H.264/AVC video coding

Abstract

Intra coding is used for reducing the spatial redundancy in video coding. H.264 supports several macroblocks of predictions for intra coding such as luma block four 16×16 modes, nine 4×4 modes and chroma block four modes, which significantly improve intra coding efficiency, but increase the encoding complexity. In order to select the best mode, we need to calculate the cost of the various modes. In this paper, a fast intra prediction mode decision for H.264/AVC video coding is proposed. Based on Laplacian, this intra prediction mode decision detects edges and selects the best mode for the block. This mode decision can shorten the time to reduce the encoding time. The experimental results show that the proposed algorithm achieves an encoding time saving of 70% on average.     

Intra mode selection in downsizing video transcoder based on H.264

An intra mode selection scheme is proposed in this work, which supports both downsizing transcoding and re‐quantization transcoding simultaneously. In the proposal, a total number of nonzero coefficients in precoded frame is used as criterion and a thresholding method is applied to select intra macroblock mode in re‐encoder. To calculate this threshold, which is related to re‐quantization parameter (denoted as Q_r), we propose a Th_I‐Q_r model which includes direct method and percentage I16MB method. In the former, an exponent model is proposed to describe relationship between the threshold and the Q_r; while in the latter, the threshold Th_I is converted into percentage of macroblocks with I16MB mode in the downsized frame (denoted as per_16), and relationship between the per_16 and the Q_r is also modeled as an exponent function. Then the two exponent models are all converted into linear regression model, and least square estimation is used to estimate the parameters of the models. Furthermore, if I4MB mode is selected for one macroblock, the intra prediction modes in precoded frame are utilized to select prediction mode for every 4 × 4 block of the macroblock in downsized frame to reduce computational complexity. We compared rate distortion performance and computational complexity of the proposed method with rate‐distortion optimization method. Simulation results demonstrate that on the precondition of compression performance of the proposal being close to the results of the rate‐distortion optimization method, the proposed method can save up to 30 and 80% in total encoding time and mode decision time, respectively. © 2009 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 19, 340–349, 2009     

Defining Embedding Distortion for Intra Prediction Mode-Based Video Steganography

In this paper, an effective intra prediction mode-based video strganography is proposed. Secret messages are embedded during the intra prediction of the video encoding without causing large embedding impact. The influence on the sum of absolute difference (SAD) in intra prediction modes (IPMs) reversion phenomenon is sharp when modifying IPMs. It inspires us to take the SAD prediction deviation (SPD) to define the distortion function. What is more, the mapping rule between IPMs and the codewords is introduced to further reduce the SPD values of each intra block. Syndrome-trellis code (STC) is used as the practical embedding implementation. Experimental results demonstrate that our proposed steganographic scheme presents high undetectability compared with existing IPMs-based steganographic approaches. It also outperforms these schemes on stego video quality.     

筒型翅片管换热器空气侧换热模型分析与实验

本文对筒型翅片管换热器的空气侧流动特点进行了理论分析,基于现有换热模型提出了一种能够反映筒型翅片管换热器结构特点的集中参数形式的换热因子关联式.通过实验对比了筒型和普通型的换热因子,对理论分析进行验证,结果表明:现有换热模型对筒型翅片管换热器的预测误差较大,平均相对误差达到81.16％;对传统换热器预测较准,平均误差为...     

基于SCADA数据和改进BP神经网络的塔筒应力预测

针对风电机组载荷监测中应变片寿命短的缺陷,基于风电场海量状态监测数据,利用遗传算法和粒子群算法对BP神经网络进行改进,建立塔筒应力预测模型,并通过综合相关系数实现输入参量的有效选择.仿真结果表明,改进后的GA-BP神经网络预测模型和PSO-BP神经网络模型,预测结果的最大、最小相对误差等指标均比BP神经网络预测模型好;...     

Intra mode decision and frame layer Lagrange multiplier adjustment scheme for H.264 based on structural similarity

H.264 takes rate distortion optimisation (RDO) technique to perform intra and inter mode decision and achieves higher coding efficiency, but the objective distortion metric such as mean square error (MSE) is employed in traditional RDO framework, which cannot acquire optimal subjective quality. In this paper, structural similarity (SSIM)-based subjective distortion is applied to RDO-based intra mode decision in H.264 I frame video coding, and a linear SSIM distortion model is firstly proposed and SSIM-based rate distortion cost function for intra mode decision is defined. Furthermore, a content adaptive frame layer Lagrange multiplier adjustment scheme is proposed to balance the tradeoff between rate and SSIM distortion better. Experimental results show that, the proposed method encodes image structural information more effectively and thus acquires better perceptual quality and subjective RDO performance compared with objective distortion-based RDO method. Under the same perceptual quality, our scheme achieves about 8·03% I frame bit rate reduction on average for various sequences over MSE-based RDO employed in JM reference software.     

Waveband selection for NIR spectroscopy analysis of soil organic matter based on SG smoothing and MWPLS methods

Savitzky-Golay (SG) smoothing and moving window partial least square (MWPLS) methods were applied to the model optimization and the waveband selection for near-infrared (NIR) spectroscopy analysis of soil organic matter. The optimal single wavelength prediction bias (OSWPB) was used to evaluate the similarity of calibration set and prediction set, and a new division method for calibration set and prediction set was proposed. SG smoothing modes were expanded to 540 kinds. The specific computer algorithm platforms for optimization of SG smoothing mode combined with PLS factor and for MWPLS method with changeable parameters were built up. The optimal waveband for soil organic matter was 1926-2032 nm, the optimal smoothing mode was the 2nd order derivative, 6th degree polynomial, 45 smoothing points, the PLS factor, RMSEP and R_P were 8, 0.260 (%) and 0.877 respectively. The prediction effect was obviously better than that in the whole spectral collecting region. To get stable results, all the optimization processes were based on the average prediction effect on 50 different divisions of calibration set and prediction set.     

钢筋混凝土空间网格结构曲率模态曲面拟合损伤识别研究

本文介绍了钢筋混凝土空间网格结构的体系组成及构造特点;提出了曲率模态曲面拟合损伤识别理论,定义了曲率模态曲面拟合损伤指标CMSFDIi和平均曲率模态曲面拟合损伤指标CMSFDIiA,通过曲率模态与曲面拟合值的差异进行损伤定位,方法仅需利用从损伤结构获得的实测数据即可进行结构损伤识别,无需利用完好结构的基本信息和理论模型;最后通过钢筋混凝土正交正放空腹网架结构实例,验证了方法的有效性。计算结果表明,本文方法不仅可以识别单位置损伤还可以识别多位置损伤,对钢筋混凝土空间网格结构的损伤识别和健康监测是可行的。     

一种基于HVS特性的视频质量评测方法

本文针对视频质量的评测应用,对传统峰值信噪比(PSNR)算法加以改进.通过在视频帧内图像和帧间图像的处理过程中引入人眼视觉系统(HVS)的主要特性,克服传统PSNR算法在序列质量检测应用方面的缺陷.方法在帧内图像处理上利用人眼对边缘轮廓失真具有较强敏感性的特点,设计了基于图像边缘的检测方案以提高对典型空域失真的检测性能;在帧间图像处理上,通过测量帧间时域能量的变化,获得序列在时域轴上的典型特征,并据此对空域检测结果进行修正.通过上述改进,算法能在保持传统PSNR算法简易性的同时,提升其检测结果与主观感受的相关性;同时算法的计算量并不复杂,易于在检测设备中实现系统集成     

A fast distance-based mode decision algorithm for 4×4 blocks in H.264/AVC intra prediction

H.264/AVC employs rate-distortion optimisation technique to achieve high coding efficiency, but it is computing-intensive. This letter presents a fast distance-based mode decision algorithm for 4×4 blocks in H.264/AVC intra prediction. Firstly, the distance between neighbouring blocks of the current block is defined. Then, the modes around up and left modes are selected as the candidate modes if the distance is small, otherwise early termination technique is used to further reduce the complexity, and either four or more modes are chosen based on the difference of rate-distortion optimisation cost. Experimental results show that our proposed algorithm can predict a 4×4 intra block by only about 3·52 modes and reduce the total encoding time by about 31·37% with negligible peak signal-to-noise ratio decrement and bit rate increment.